1. Field of the Invention
The present invention relates to an electric hand control especially for electrically adjustable hospital and care beds.
2. The Prior Art
As examples of adjustable hospital beds, EP 0 488 552 A1 Huntleigh Technology plc and U.S. Pat. No. 4,425,673 B-W Health Products, Inc. can be mentioned. Typically, there are two controls for the bed, a hand control with which the patient can adjust the bed to the wanted position and a control panel at the end of the bed where the hospital staff can make adjustments of the bed, among these, adjustment in excess of the adjustments possibilities of the patient. At the same time, the staff can block medical positions that are not allowed for the patient in question, so that the patient cannot inadvertently activate a position not allowed. For instance, raising the leg section by a patient who has a thigh bone fracture.
Instead of a separate hand control and control panel, it can be desirable to have only the hand control. For care beds which typically are not as technically advanced as hospital beds and which are only equipped with a hand control, it can also be expedient to have a blocking of certain adjustment functions.
In CH 681 833 Magnetic Elektromotoren AG a hand control for hospital beds with a blocking arrangement for various functions is mentioned. The control is a pneumatic control, and the keys are placed in pairs with one key for activation of the function and the other for reversing to the initial position. The blocking arrangement works strictly mechanically with a pin with two wings placed between two sets of contacts. By turning the pin with a key for that purpose, the two wings can be brought under a flange on the keys and block the pressing of the keys. In an electric hand control from the same company described in CH 691 638 Magnetic Elektromotoren AG the keys are blocked completely electronically. For this purpose the hand control contains two read-switches, which can be activated with a key comprising two magnets, one for each of the two read-switches. When the read-switch is activated, the control goes into programming mode, where the control can be programmed into locking and unlocking the operation keys.
The invention concerns hand controls where small square brick shaped switches with a pushbutton on the top side can be used, the switches being “Tactile Switches” or “Tact Switches”. The switches are placed under a springy tongue in the top side of the hand control, on which a foil with graphics localizing the key and its function is mounted. By pressing the foil the tongue is pressed inwards and affects the pushbutton on the switch. The migration on the pushbutton is very modest, that is in the same size as the tolerance on the subjects, which makes a mechanical locking difficult. This is also reflected in the known technology mentioned above, where a mechanical solution is chosen for the pneumatic hand control and an electrical solution for the electric hand control.
The object of the invention is to provide an electric hand control with electric locking of the keys.